list manipulation - Reverse DeleteDuplicates using Information from Tally

I have a list of values, e.g., {1, 1, 1, 2, 2, 3, 3, 4, 4, 4, 4, 4, 4, 5}. I delete the duplicates with

DeleteDuplicates[{1, 1, 1 ,2, 2, 3, 3, 4, 4, 4, 4, 4, 4, 5}];

{1, 2, 3, 4, 5}

I want to perform some calculations on each value and at the end reverse the process of deleting.

From Tally I know, how often the elements appear:

Tally[{1, 1, 1, 2, 2, 3, 3, 4, 4, 4, 4, 4, 4, 5}];

{{1, 3}, {2, 2}, {3, 2}, {4, 5}, {5, 1}}

Now, from the calculations I have the new list {12, 14, 15, 16, 17}. I want to reverse the process of DeleteDuplicates on this list. Means: {{12,3},{14,2},{15,2},{16,5},{17,1}} -> So, that I get:

{12, 12, 12, 14, 14, 15, 15, 16, 16, 16, 16, 17}.

I want to do that, because the calculations take very long and I want to calculate duplicates two times.

Answer

tal = {{1, 3}, {2, 2}, {3, 2}, {4, 5}, {5, 1}};

lis = {12, 14, 15, 16, 17};

Flatten @ MapThread[Table[#1, {#2}] &, {lis, Last /@ tal}]

{12, 12, 12, 14, 14, 15, 15, 16, 16, 16, 16, 16, 17}

Flatten[ConstantArray @@@ Transpose[{lis, Last /@ tal}]]

Comments

plotting - How to draw lines between specified dots on ListPlot?

I would like to create a plot where I have unconnected dots and some connected. So far, I have figured out how to draw the dots. My code is the following: ListPlot[{{1, 1}, {2, 2}, {3, 3}, {4, 4}, {1, 4}, {2, 5}, {3, 6}, {4, 7}, {1, 7}, {2, 8}, {3, 9}, {4, 10}, {1, 10}, {2, 11}, {3, 12}, {4,13}, {2.5, 7}}, Ticks -> {{1, 2, 3, 4}, None}, AxesStyle -> Thin, TicksStyle -> Directive[Black, Bold, 12], Mesh -> Full] I have thought using ListLinePlot command, but I don't know how to specify to the command to draw only selected lines between the dots. Do have any suggestions/hints on how to do that? Thank you. Answer One possibility would be to use Epilog with Line : ListPlot[ {{1, 1}, {2, 2}, {3, 3}, {4, 4}, {1, 4}, {2, 5}, {3, 6}, {4, 7}, {1, 7}, {2, 8}, {3, 9}, {4, 10}, {1, 10}, {2, 11}, {3, 12}, {4, 13}, {2.5, 7}}, Ticks -> {{1, 2, 3, 4}, None}, AxesStyle -> Thin, TicksStyle -> Directive[Black, Bold, 12], Mesh -> Full, Epilog -> { Line[ ...

list manipulation - Selecting multiple columns from a matrix?

Sample data: data = { {{2013, 1, 1}, 24.13, 167.67, 231.82}, {{2013, 1, 2}, 32.15, 170.92, 225.99}, {{2013, 1, 3}, 35.43, 172.68, 221.67}, {{2013, 1, 4}, 36.73, 173.05, 218.32}, {{2013, 1, 5}, 58.19, 165.96, 197.05}, {{2013, 1, 6}, 69.99, 163.50, 187.52}, {{2013, 1, 7}, 71.37, 154.21, 175.58}, {{2013, 1, 8}, 72.51, 149.66, 163.25}}; I want a DateListPlot with three graphs, so for a matrix formed by columns 1 and 2, one for columns 1 and 3, and 1 for columns 1 and 4. At the moment I'm using this code: data2 = Transpose[{data[[All, 1]], data[[All, 2]]}]; data3 = Transpose[{data[[All, 1]], data[[All, 3]]}]; data4 = Transpose[{data[[All, 1]], data[[All, 4]]}]; DateListPlot[{data2, data3, data4}, Joined -> True, Filling -> {3 -> {1}}] but I have a hunch that this can be done more efficiently. I don't like the Transpose s in particular. Any ideas? edit (for extra credit) What if I need to multiply the second column by 2, which in my solution is simp...

plotting - How to draw some 2D curves in a 3D plot?

I want to plot several 2D curves ( Sin[x] at y=0 , Cos[x] at y=1 ) in a 3D plot, what function should i use? f[x_, y_] := Piecewise[{{0, y 0}, {Sin[x], y == 0}}] g[x_, y_] := Piecewise[{{0, y 1}, {Cos[x], y == 1}}] Plot3D[{f[x, y], g[x, y]}, {x, 0, 10}, {y, 0, 10}] doesn't work. Any ideas? Answer ParametricPlot3D[{{Sin[u], 0, u}, {Cos[u], 1, u}}, {u, 0, 20}, BoxRatios -> 1, PlotRange -> {{-2, 2}, {-.5, 2}, {0, 20}}] === update - general thoughts === I've seen the comments to this question and a few other approaches to the waterfall (or wire) plot are given in this question: Plotting several functions . Also I cannot not mention one of my favorite Mathematica blogs - Archery with this post on the story of discovery of 1st pulsar and an its infamous graphics - code is given in the post:

Blog

Search This Blog